Fuel injection pump for internal combustion engines

ABSTRACT

What follows is a description in exemplary form of an improved fuel injection pump which includes a pump piston, a pump working chamber, a relief channel operatively associated with the working chamber, a cam drive for driving the pump piston, a fuel feed pump synchronously driven with the pump piston for feeding fuel to the working chamber in dependence on engine rpm, a control piston and a pressure regulating valve for the fuel feed pump. According to the present invention a portion of the fuel feed quantity of the fuel injection quantity is caused to flow off through the relief channel in order to alter the fuel injection quantity by regulating the relief channel and by displacing the cam drive by the control piston under the influence of the feed pressure from the fuel feed pump to thereby change the moment of injection. In addition the resultant pressure of the fuel feed quantity which flows through the relief channel serves as a control pressure for the pressure regulating valve.

Oct. 7, 1975 1 FUEL INJECTION PUMP FOR INTERNAL COMBUSTION ENGINES [75] Inventor: Katashi Okamoto, Kariya, Japan [73] Assignee: Robert Bosch G.m.b.I-L, Stuttgart,

Germany [22] Filed: Nov. 13, 1973 21 Appl. No.: 415,411

Foreign Application Priority Data Nov. 14, 1972 Japan 47-114575 123/139 AQ, 139 P, 140 MC, 139 R140 FG 3,630,643 12/1971 Ehiem et al 417/289 Primary ExaminerJohn J. Vrablik Attorney, Agent, or Firm-Edwin E. Greigg [57] ABSTRACT What follows is a description in exemplary form of an improved fuel injection pump which includes a pump piston, a pump working chamber, a relief channel operatively associated with the working chamber, a cam drive for driving the pump piston, 21 fuel feed pump synchronously driven with the pump piston for feeding fuel to the working chamber in dependence on engine rpm, a control piston and a pressure regulating valve for the fuel feed pump. According to the present invention a portion of the fuel feed quantity of the fuel injection quantity is caused to flow off through the relief channel in order to alter the fuel injection quantity by regulating the relief channel and by displacing the cam drive by the control piston under the influence of [561 Memes 31121163111211?12125321 ifi alllfin ihl fiifl UNITED STATES PATENTS tant pressure of the fuel feed quantity which flows BiSchOff through the relief channel erves as a ontrol pressure 2,765,741 10/1956 Hogeman 41 7/289 for the pressure regulating valve 2,810,376 10/1957 Aldmger 417/294 3,358,662 12/1967 Kulke 123/139 R 4 Claims, 2 Drawing Figures 25b 34 l V 23 27 n 2213 33 v 29 n 48b 43 30 2 5 28G l 37 47 470 44 t- I l g a V\\ I. 9

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. 6 3S 5 26 5 SCI 8 E I J Sheet 1 of2 Oct. 7,1975

US. Patent U.S. Pater 1t Oct. 7,1975 Sheet20f2 3,910,724

FUEL INJECTION PUMP FOR INTERNAL COMBUSTION ENGINES BACKGROUND OF THE INVENTION The present invention relates to a fuel injection pump for internal combustion engines having a pump piston driven by a cam drive, in which a portion of the fuel feed quantity flows off in order to alter the fuel injection quantity by regulating a relief channel of the pump working chamber, and changing the moment of injection by displacing the cam drive with a piston which is acted upon by the rpm dependent pressure of a pump driven synchronously with the injection pump piston.

In injection pumps of this construction the injection moment, as the rpm of the internal combustion engine provided with such an injection pump increases, is shifted to early" by means of increasing hydraulic pressure. Although the injection moment was controlled in the above described manner, that is in accordance with the rpm of the internal combustion engine, the injection moment has not been controlled in accordance with engine load. In practice the injection moment was set in such a manner that the optimum injection moment was achieved either at the full load setting of the internal combustion engine or at the' partial load setting thereof. Thus, for example, if the injection according to the optimum injection moment was set for full load, then the injection moment occurred too early with respect to the partial load range, thereby causing increased combustion noise. If, on the other hand, the injection moment was optimized to correspond to the partial load range of the internal combustion engine, then it occurred too late with respect to the full load range, thereby resulting in a power loss.

OBJECTS AND SUMMARY OF THE INVENTION It is, therefore, an object of the present invention to eliminate the above noted disadvantages and to provide a fuel injection pump for internal combustion engines in which the injection moment can be controlled in accordance with the load of the internal combustion engine, and by means of which an optimum injection moment is obtained at any given time and for all operational conditions of an internal combustion engine.

This and other objects are achieved in accordance with the present invention by the provision of a pressure regulating valve for the feed pressure of a fuel feed pump, with the resultant pressure of the fuel quantity flowing off through a relief channel serving as the regulating pressure for the pressure regulating valve.

An advantageous embodiment of the present invention consists in that the control point of the relief channel is connected to the fuel reservoir through a return line'having a throttle wherein, downstream of the throttle, a connecting line branches off to the pressure regulating valve. A regulating pressure can be advantagesously built up by utilization of the above described throttle, which pressure acts upon the pressure regulating valve through the connecting line.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 illustrates partially in cross section the essential cooperating elements of the improved fuel injection pump for internal combustion engines including a pressure regulating valve according to one embodiment of the present invention. 7

FIG. 2 illustrates partially in cross section the essential cooperating elements of the improved fuel injection pump for internal combustion engines including a pressure regulating valve according to another embodiment of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT In a pump housing 1 there is provided a drive shaft 2 which serves to drive a pump piston 5. The pump piston 5 is pressed into the cam plate 6 by means of an axial spring 35, and is thereby connected for rotation therewith. The cam plate 6 is rotated by means of the drive shaft 2, and is thereby driven over rollers 3 which rest on a rotatably disposed roller ring 4 in the pump housing 1. As a result, the piston 5 is simultaneously placed into both rotation and reciprocating motion by the cam plate 6. The cam plate 6 is reciprocated by the contact with the rollers 3 in a well known manner. See, for example,- US. Pat. No. 3,630,643.

A revolving slide ring 7 arranged to be slidable in the axial direction of the piston 5, controls a transverse bore 5b of the piston 5. The bore 5b is connected with a relief channel 50 developed as an axial pocket bore. During the suction stroke of the pump piston 5 in the pump cylinder 36 disposed in the pump housing 1, fuel is fed through a fuel suction channel 9, a second traverse bore 9a in the pump piston 5 to the relief channel 50, and through the relief channel 5a into a pump working chamber 10. During the feed stroke of the pump piston 5, fuel is fed through a traverse distributor grooveSc, which is connected with the pump working chamber 10, into one of the feed channels 8 and from there through a relief valve 11 to one of the injection nozzles 12 in a fuel injection engine E. The fuel feed period, that is the period during which the fuel is fed to the injection nozzle 12, is that period of time which starts from the moment in which, for example, the feed channel 8, as it can be seen in the drawing, is connected with the traverse distributor groove 50 (injection beginning), and lasts to the moment when the transverse bore 5b is freed from the revolving slide ring 7 during the feed stroke of the piston 5 (injection end).

A pin 14 is provided on the roller ring 4 on which a lever 13 is mounted for rotation in a plane which is directed vertically to the plane of the drawing. The roller ring 4 is rotated about the axis of the drive shaft 2 also in a plane which is directed vertically to the plane of the drawing. The roller ring 4 is rotated by means of the rotating motion of the lever 13. The result thereof is that the correlation of the rollers 3 with the cam of the cam plate 6 is altered, so that the moment at which, for example, the pump piston 5 starts its stroke, is also altered with reference to the angle of rotation of the drive shaft 2. i

A control piston 16 is disposed in a cylinder 15 in the pump'housing l. The lever l3is actuated by displacing the piston 16. It is noted that the control piston 16 is shown rotated by'90 for clarity of discussion. As such, the piston 16 moves in a direction which is vertical to the plane of the drawing. A rod 39 is secured to the piston 16 so as to move solidly therewith and a connecting rod 40 is provided between the rod 39 and the lever 13 to transmit the movement of the piston 16 to the lever 13, thus rotating the lever 13 in the plane which is vertical to the plane of the drawing.

The end face 16 of the piston 16 together with the cylinder defines a pressure chamber 21, while the end face 16" is acted upon by a spring 37 situated within the chamber 38 defined by the end face 16" and the cylinder 15. The pressure chamber 21 is connected by a pressure line with a first feed pump 17 actuated by the internal combustion engine E. The feed pump 17 draws fuel from a fuel reservoir 18 through a pipe line 19 and feeds the fuel through the pressure line 20 into the pressure chamber 21. The piston 16 is thus displaced more or less against the force of the spring 37 in accordance with the magnitude of the feed pressure, so that the lever 13 is moved correspondingly and the roller ring 4 is turned. A connecting line 22a branches off from the pressure line 20 and leads to a pressure control valve 32. From the control valve 32 a connecting line 22b leads to a bypass line b, which line discharges into the fuel reservoir 18.

The supply of fuel to the fuel injection pump occurs through a second feed pump 23, the pressure side of which is connected with the fuel suction channel 9, while the suction side thereof is connected with the fuel reservoir 18 through a channel 34. The second fuel pump 23 is also actuated by the internal combustion engine E, and it should be noted that it is of course possible to forego the second fuel pump 23 and to additionally connect the feed side of the fuel pump 17 with the fuel suction channel 9 (FIG. 2).

When the traverse bore 5b of the piston 5 comes to rest on the right side (in the drawing) of the revolving slide ring 7 and is thereby opened, the flow-off fuel flows through the transverse bore 5b into a bypass chamber 24. From the bypass chamber 24 the fuel is led through a return line 25a to a connecting line 31 to the control valve 32.

The displacement of the revolving slide ring 7 occurs by means of an eccentric pin 41, a rod 42 and a lever 26. The rod 42 is rotatably mounted on the housing. The eccentric pin 41 engages a recess 70 of the ring 7. A shield element 43 is provided between the housing and the rod 42. The lever 26 connects the rod 42 and an acceleration lever (not shown). Therefore the movement of the acceleration lever is converted to displace the ring 7 to the left or to the right in accordance with the acceleration lever.

Although the above described construction is for the most part known, is has been provided with means according to the present invention which controls the fuel feed pressure of the first fuel pump 17 in dependence on the load of the internal combustion engine E. This substantially happens because of the pressure control valve 32.

The pressure control valve 32 comprises a cyliner 27 in which a piston 28 is arranged to be slidably displaced against the force of a spring 30. A pressure chamber 29 is defined by the piston 28 and one end of the cylinder 27. The pressure chamber 29 is connected with the bypass line 25a through the connecting line 31. A radial bore 28a is provided in the piston 28 for connecting the feed side of the fuel pump 17 through the connecting line 22a to the connecting line 22b and thus to the return line portion 2512. Instead of the radial bore 28a in the piston 28 there could also be, of course, provided an annular slot. The return line portions 25a and 25b are connected together through a throttle 33.

In the above described construction the fuel, which is present in the fuel reservoir '18, is fed through the first fuel pump 17 and then through the second fuel pump 23 under a pressure corresponding to the rpm of the internal combustion engine E. The fuel fed through the second fuel pump 23 enters the pump working chamber 10 through the fuel suction channel 9 and from there it is fed under pressure through the injection nozzles 12 and ultimately to the internal combustion engine E by displacing the piston 5 to the right (in the drawing).

At the moment when the transverse bore 5b is freed from the revolving slide ring 7, as a result of the stroke of the piston 5 and the fuel discharging into the bypass chamber 24, the fuel injection ends. But since the location of the revolving slide ring 7 depends on the location of the acceleration lever of the internal combustion engine E and is displaceable by means of the lever 26, the above mentioned termination of the fuel injection can be regulated, in dependence on the load of the internal combustion engine E. In similar manner the fuel quantity flowing through the transverse bore 5b is a measure of the load of the internal combustion engine E. Alternatively, the fuel fed from the fuel reservoir 18 through the first fuel pump 17 passes through the pressure line 20 and enters the pressure chamber 21; and can flow also through the pressure line 20, the connection line 22a, the bore 28a, the connection line 22b, and the bypass line 25b back into the fuel reservoir 18. The feed pressure in the chamber 21 acts on the piston 16 and displaces it to the right. In conjunction with this the roller ring 4 turns about the axis of the drive shaft 2 by means of the lever 13. Thus the cycle of the reciprocating movement of the piston 5 is altered. As a consequence of this, the injection moment of the fuel injection is also changed in the internal combustion engine E. As a further consequence the fuel feed pressure of the first fuel pump 17 and the second fuel pump 23 is also changed in dependence on the rpm of the internal combustion engine E, and the above mentioned injection moment is changed therefore also in dependence on the rpm of the internal combustion engine E.

There is still provided a pressure regulating valve 32 in which valve the pressure chamber 29 is connected with the bypass chamber 24 by the connecting line 31 and the return line 25a. A swivel joint 44 is further mounted on the housing to connect the bypass chamber 24 and return line 25a. A bushing 45 is inserted into a fuel passage 46. A bolt 48 having a first passage 48a in an axial direction and a second passage 48b in a radial direction is also secured to the bushing 45 with a swivel nipple 47 which has an annular groove 47b communicating the second passage 48b.

The fuel flowing through the transverse bore 5b of the relief channel 5a into the bypass chamber 24, the discharge of which to the fuel reservoir 18 is checked by the throttle 33, generates a pressure which acts upon the-chamber 29. As a result the piston 28 is moved against the force of the spring 30 according to this fuel pressure and this results in altering the cross section of the traverse flow between the connecting line 22a or the connecting line 22b and the bore 28a. This means that simultaneously also the amount of fuel discharging through the pressure regulating valve 32 is changed.

ring 7. Thus is may be said that the fuel injection moment can be controlled not only in dependence on the rpm of the internal combustion engine E but also in dependence on the load of the internal combustion engine E. This is so because the fuel pressure regulating the pressure regulating valve 32 depends on the position of the revolving slide ring 7 or the load of the internal combustion engine E.

The construction described operates follows: when during a load increase in the internal combustion engine E the revolving slide ring 7 is caused to move to the right (in the drawing), the termination of the fuel injection is delayed and the amount of the fuel injected into the internal combustion engine E is increased. The amount of fuel flowing off into the bypass chamber 24 is simultaneously reduced, and the pressure in the pressure chamber 29 is also reduced so that the piston 28 is moved to the right (in the drawing) by the force of the spring 30. Thereby the passage cross section between the connecting lines 22a and 22b is reduced and the pressure of the fuel passing through the first fuel feed pump 17 is increased. The increase in this fuel pressure causes the displacement of the piston 16 to the right against the force of the spring 37, whereby the fuel injection moment experiences an angular advance. It should be understood that in the case of a load decrease in the internal combustion engine E the fuel injection moment will experience an angular retraction in opposition to the case described above.

In the preferred embodiment of the above specification of the present invention there has been demonstrated a distributor fuel injection pump of the construction in which the revolving slide ring 7 is displaced by an acceleration lever of the internal combustion engine E and thereby the termination of the fuel injection is altered. Obviously, the present invention may be applied also to other embodiments of fuel injection pumps, for example, to a construction in which the above mentioned revolving slide ring 7 is displaced by the fuel feed pressure of a feed pump.

Since according to the present invention in the above described embodiment the fuel injection moment can be regulated not only in dependence on the rpm but also on the load of the internal combustion engine E, the present invention has a substantial advantage in that in this manner it is possible to inject the fuel into the internal combustion engine E at any given time and at that injection moment which is the most favorable for that operational condition of the internal combustion engine E.

What is claimed is:

1. In a fuel injection pump for internal combustion engines, including:

a. a pump piston;

b. means defining an injection pump working chamber;

c. means defining an injection pump relief channel,

said relief channel being operatively associated with said working chamber;

d. cam drive means for driving said pump piston;

e. fuel feed pump means synchronously driven with said pump piston for feeding fuel through said relief channel to said working chamber in dependence on engine rpm;

f. a control piston;

g. means connecting said control piston to said fuel feed pump means;

h. means connecting said control piston to said cam drive means;

i. means defining a bypass chamber; and

j. means controlling the extent to which fuel flows through said relief channel to said bypass chamber, wherein a portion of the fuel feed quantity of the fuel injection quantity is caused to flow off through said relief channel to said bypass chamber in order to alter the fuel injection quantity by regulating said relief channel and by displacing said cam drive means by said control piston under the improvement comprising:

1. pressure regulating valve means;

2. means connecting said pressure regulating valve means to said bypass chamber; and

3. means connecting said pressure regulating valve means to said fuel feed pump means to regulate the pressure thereof, wherein the resultant pressure of the fuel quantity which flows off through said relief channel serves as a control pressure for said pressure regulating valve means.

2. The fuel injection nump according to claim 1, further comprising a fuel reservoir, a bypass line for bypassing said pressure regulating valve means and having a throttle, a connecting means connecting said bypass line to said bypass chamber wherein said connecting means serves as a control location, wherein said control location is connected with the fuel reservoir by said bypass line, and wherein said connecting line branches off from said bypass line to said pressure control valve downstream from said throttle.

3. The fuel injection pump according to claim 2, wherein said means connecting said pressure regulating valve means to said fuel feed pump means includes a connecting line, and; wherein said pressure control valve comprises a cylinder, a spring, a piston displaceable by the regulating pressure within said cylinder against the force of said spring, said piston including a bore for controlling said connecting line leading from the feed pressure side of said feed pump means through said control valve cyiinder to said fuel reservoir.

4. The fuel injection pump according to claim 3, wherein said controlling means comprises a revolving slide ring and a fuel quantity altering lever, wherein said relief channel passes through said pump piston and includes a transverse bore portion with said transverse bore being controllable by means of said revolving slide ring, and wherein said ring is adjustable by means of said fuel quantity altering lever.

UNITED STATES PATENT AND TRADEMARK OFFICE CERTIFICATE OF CRECTION PATENT N0. 3, 910, 724

DATED October 7, 1975 INV ENTOR(S) I KATASHI OKAMOTO It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

[73] Assignee:"ROBERT BOSCH G,M.BH, Stuttgart,

Germany should be NIPPODENSO CO., L'IDa Kariya-shi, Aichi-Ken, JAPAN- En'gncd and Salcd this Second Day Of Sefltember I980 [SEAL] SIDNEY A. DIAMOND Arresting Oflicer Commissioner of Patents and Trademarks 

1. In a fuel injection pump for internal combustion engines, including: a. a pump piston; b. means defining an injection pump working chamber; c. means defining an injection pump relief channel, said relief channel being operatively associated with said working chamber; d. cam drive means for driving said pump piston; e. fuel feed pump means synchronously driven with said pump piston for feeding fuel through said relief channel to said working chamber in dependence on engine rpm; f. a control piston; g. means connecting said control piston to said fuel feed pump means; h. means connecting said control piston to said cam drive means; i. means defining a bypass chamber; and j. means controlling the extent to which fuel flows through said relief channel to said bypass chamber, wherein a portion of the fuel feed quantity of the fuel injection quantity is caused to flow off through said relief channel to said bypass chamber in order to alter the fuel injection quantity by regulating said relief channel and by displacing said cam drive means by said control piston under the improvement comprising:
 1. pressure regulating valve means;
 2. means connecting said pressure regulating valve means to said bypass chamber; and
 3. means connecting said pressure regulating valve means to said fuel feed pump means to regulate the pressure thereof, wherein the resultant pressure of the fuel quantity which flows off through said relief channel serves as a control pressure for said pressure regulating valve means.
 2. means connecting said pressure regulating valve means to said bypass chamber; and
 2. The fuel injection pump according to claim 1, further comprising a fuel rEservoir, a bypass line for bypassing said pressure regulating valve means and having a throttle, a connecting means connecting said bypass line to said bypass chamber wherein said connecting means serves as a control location, wherein said control location is connected with the fuel reservoir by said bypass line, and wherein said connecting line branches off from said bypass line to said pressure control valve downstream from said throttle.
 3. The fuel injection pump according to claim 2, wherein said means connecting said pressure regulating valve means to said fuel feed pump means includes a connecting line, and wherein said pressure control valve comprises a cylinder, a spring, a piston displaceable by the regulating pressure within said cylinder against the force of said spring, said piston including a bore for controlling said connecting line leading from the feed pressure side of said feed pump means through said control valve cylinder to said fuel reservoir.
 3. means connecting said pressure regulating valve means to said fuel feed pump means to regulate the pressure thereof, wherein the resultant pressure of the fuel quantity which flows off through said relief channel serves as a control pressure for said pressure regulating valve means.
 4. The fuel injection pump according to claim 3, wherein said controlling means comprises a revolving slide ring and a fuel quantity altering lever, wherein said relief channel passes through said pump piston and includes a transverse bore portion with said transverse bore being controllable by means of said revolving slide ring, and wherein said ring is adjustable by means of said fuel quantity altering lever. 